mod/lti/servicelib.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * Utility code for LTI service handling.
  19  *
  20  * @package mod_lti
  21  * @copyright  Copyright (c) 2011 Moodlerooms Inc. (http://www.moodlerooms.com)
  22  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23  * @author     Chris Scribner
  24  */
  25
  26 defined('MOODLE_INTERNAL') || die;
  27
  28 require_once($CFG->dirroot.'/mod/lti/OAuthBody.php');
  29
  30 // TODO: Switch to core oauthlib once implemented - MDL-30149
  31 use moodle\mod\lti as lti;
  32
  33 define('LTI_ITEM_TYPE', 'mod');
  34 define('LTI_ITEM_MODULE', 'lti');
  35 define('LTI_SOURCE', 'mod/lti');
  36
  37 function lti_get_response_xml($codemajor, $description, $messageref, $messagetype) {
  38     $xml = new SimpleXMLElement('<?xml version="1.0" encoding="UTF-8"?><imsx_POXEnvelopeResponse />');
  39     $xml->addAttribute('xmlns', 'http://www.imsglobal.org/services/ltiv1p1/xsd/imsoms_v1p0');
  40
  41     $headerinfo = $xml->addChild('imsx_POXHeader')->addChild('imsx_POXResponseHeaderInfo');
  42
  43     $headerinfo->addChild('imsx_version', 'V1.0');
  44     $headerinfo->addChild('imsx_messageIdentifier', (string)mt_rand());
  45
  46     $statusinfo = $headerinfo->addChild('imsx_statusInfo');
  47     $statusinfo->addchild('imsx_codeMajor', $codemajor);
  48     $statusinfo->addChild('imsx_severity', 'status');
  49     $statusinfo->addChild('imsx_description', $description);
  50     $statusinfo->addChild('imsx_messageRefIdentifier', $messageref);
  51     $incomingtype = str_replace('Response','Request', $messagetype);
  52     $statusinfo->addChild('imsx_operationRefIdentifier', $incomingtype);
  53
  54     $xml->addChild('imsx_POXBody')->addChild($messagetype);
  55
  56     return $xml;
  57 }
  58
  59 function lti_parse_message_id($xml) {
  60     $node = $xml->imsx_POXHeader->imsx_POXRequestHeaderInfo->imsx_messageIdentifier;
  61     $messageid = (string)$node;
  62
  63     return $messageid;
  64 }
  65
  66 function lti_parse_grade_replace_message($xml) {
  67     $node = $xml->imsx_POXBody->replaceResultRequest->resultRecord->sourcedGUID->sourcedId;
  68     $resultjson = json_decode((string)$node);
  69
  70     $node = $xml->imsx_POXBody->replaceResultRequest->resultRecord->result->resultScore->textString;
  71
  72     $score = (string) $node;
  73     if ( ! is_numeric($score) ) {
  74         throw new Exception('Score must be numeric');
  75     }
  76     $grade = floatval($score);
  77     if ( $grade < 0.0 || $grade > 1.0 ) {
  78         throw new Exception('Score not between 0.0 and 1.0');
  79     }
  80
  81     $parsed = new stdClass();
  82     $parsed->gradeval = $grade * 100;
  83
  84     $parsed->instanceid = $resultjson->data->instanceid;
  85     $parsed->userid = $resultjson->data->userid;
  86     $parsed->launchid = $resultjson->data->launchid;
  87     $parsed->sourcedidhash = $resultjson->hash;
  88
  89     $parsed->messageid = lti_parse_message_id($xml);
  90
  91     return $parsed;
  92 }
  93
  94 function lti_parse_grade_read_message($xml) {
  95     $node = $xml->imsx_POXBody->readResultRequest->resultRecord->sourcedGUID->sourcedId;
  96     $resultjson = json_decode((string)$node);
  97
  98     $parsed = new stdClass();
  99     $parsed->instanceid = $resultjson->data->instanceid;
 100     $parsed->userid = $resultjson->data->userid;
 101     $parsed->launchid = $resultjson->data->launchid;
 102     $parsed->sourcedidhash = $resultjson->hash;
 103
 104     $parsed->messageid = lti_parse_message_id($xml);
 105
 106     return $parsed;
 107 }
 108
 109 function lti_parse_grade_delete_message($xml) {
 110     $node = $xml->imsx_POXBody->deleteResultRequest->resultRecord->sourcedGUID->sourcedId;
 111     $resultjson = json_decode((string)$node);
 112
 113     $parsed = new stdClass();
 114     $parsed->instanceid = $resultjson->data->instanceid;
 115     $parsed->userid = $resultjson->data->userid;
 116     $parsed->launchid = $resultjson->data->launchid;
 117     $parsed->sourcedidhash = $resultjson->hash;
 118
 119     $parsed->messageid = lti_parse_message_id($xml);
 120
 121     return $parsed;
 122 }
 123
 124 function lti_update_grade($ltiinstance, $userid, $launchid, $gradeval) {
 125     global $CFG, $DB;
 126     require_once($CFG->libdir . '/gradelib.php');
 127
 128     $params = array();
 129     $params['itemname'] = $ltiinstance->name;
 130
 131     $grade = new stdClass();
 132     $grade->userid   = $userid;
 133     $grade->rawgrade = $gradeval;
 134
 135     $status = grade_update(LTI_SOURCE, $ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, 0, $grade, $params);
 136
 137     $record = $DB->get_record('lti_submission', array('ltiid' => $ltiinstance->id, 'userid' => $userid, 'launchid' => $launchid), 'id');
 138     if ($record) {
 139         $id = $record->id;
 140     } else {
 141         $id = null;
 142     }
 143
 144     if (!empty($id)) {
 145         $DB->update_record('lti_submission', array(
 146             'id' => $id,
 147             'dateupdated' => time(),
 148             'gradepercent' => $gradeval,
 149             'state' => 2
 150         ));
 151     } else {
 152         $DB->insert_record('lti_submission', array(
 153             'ltiid' => $ltiinstance->id,
 154             'userid' => $userid,
 155             'datesubmitted' => time(),
 156             'dateupdated' => time(),
 157             'gradepercent' => $gradeval,
 158             'originalgrade' => $gradeval,
 159             'launchid' => $launchid,
 160             'state' => 1
 161         ));
 162     }
 163
 164     return $status == GRADE_UPDATE_OK;
 165 }
 166
 167 function lti_read_grade($ltiinstance, $userid) {
 168     global $CFG;
 169     require_once($CFG->libdir . '/gradelib.php');
 170
 171     $grades = grade_get_grades($ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, $userid);
 172
 173     if (isset($grades) && isset($grades->items[0]) && is_array($grades->items[0]->grades)) {
 174         foreach ($grades->items[0]->grades as $agrade) {
 175             $grade = $agrade->grade;
 176             $grade = $grade / 100.0;
 177             break;
 178         }
 179     }
 180
 181     if (isset($grade)) {
 182         return $grade;
 183     }
 184 }
 185
 186 function lti_delete_grade($ltiinstance, $userid) {
 187     global $CFG;
 188     require_once($CFG->libdir . '/gradelib.php');
 189
 190     $grade = new stdClass();
 191     $grade->userid   = $userid;
 192     $grade->rawgrade = null;
 193
 194     $status = grade_update(LTI_SOURCE, $ltiinstance->course, LTI_ITEM_TYPE, LTI_ITEM_MODULE, $ltiinstance->id, 0, $grade, array('deleted'=>1));
 195
 196     return $status == GRADE_UPDATE_OK;
 197 }
 198
 199 function lti_verify_message($key, $sharedsecrets, $body, $headers = null) {
 200     foreach ($sharedsecrets as $secret) {
 201         $signaturefailed = false;
 202
 203         try {
 204             // TODO: Switch to core oauthlib once implemented - MDL-30149
 205             lti\handleOAuthBodyPOST($key, $secret, $body, $headers);
 206         } catch (Exception $e) {
 207             $signaturefailed = true;
 208         }
 209
 210         if (!$signaturefailed) {
 211             return $secret;//Return the secret used to sign the message)
 212         }
 213     }
 214
 215     return false;
 216 }
 217
 218 function lti_verify_sourcedid($ltiinstance, $parsed) {
 219     $sourceid = lti_build_sourcedid($parsed->instanceid, $parsed->userid, $parsed->launchid, $ltiinstance->servicesalt);
 220
 221     if ($sourceid->hash != $parsed->sourcedidhash) {
 222         throw new Exception('SourcedId hash not valid');
 223     }
 224 }
 225
 226 /**
 227  * Extend the LTI services through the ltisource plugins
 228  *
 229  * @param stdClass $data LTI request data
 230  * @return bool
 231  * @throws coding_exception
 232  */
 233 function lti_extend_lti_services($data) {
 234     $plugins = get_plugin_list_with_function('ltisource', $data->messagetype);
 235     if (!empty($plugins)) {
 236         try {
 237             // There can only be one
 238             if (count($plugins) > 1) {
 239                 throw new coding_exception('More than one ltisource plugin handler found');
 240             }
 241             $callback = current($plugins);
 242             call_user_func($callback, $data);
 243         } catch (moodle_exception $e) {
 244             $error = $e->getMessage();
 245             if (debugging('', DEBUG_DEVELOPER)) {
 246                 $error .= ' '.format_backtrace(get_exception_info($e)->backtrace);
 247             }
 248             $responsexml = lti_get_response_xml(
 249                 'failure',
 250                 $error,
 251                 $data->messageid,
 252                 $data->messagetype
 253             );
 254
 255             header('HTTP/1.0 400 bad request');
 256             echo $responsexml->asXML();
 257         }
 258         return true;
 259     }
 260     return false;
 261 }